If I am not mistaken synthetic is not recommended for jeeps because it cost more and apparently does not provide any additional life or performace and can be mildy corrosive to the metals used in the Jeep diff.

That might be total BS... I have never changed my diff fluid (Yet.. And now I am replacing the axles... LOL) I just read that somewhere.

Ya, that's what's so confusing. There are many who use ONLY synthetics and swear by them, and then some disagree. I was once an Amsoil kinda guy, but Mobil 1 is so much easier to get when I want to do something at the spur of the moment. Mobil 1 makes a gear lube with the friction additives often mentioned in write ups here and elsewhere.

Yea I hate mob1 but its only cause I work for Ashland Inc who owns Valvoline. BUT my guys at the Valvoline Instant Oil Change stations tell me that 75w140syn is the only way to go if you are doing any towing or offroading. I know that you might not like Valvoline but I definately will follow my mechanic friends and say use a synthetic if you are pushing it in the dirt or on the rocks.